staging: zram: make global var "num_devices" use unique name

The global variable "num_devices" is too general to be
global. This patch switches the name to be "zram_num_devices".

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
staging: zram: fix zram locking

Currently init_lock only prevents concurrent execution of zram_init_device()
and zram_reset_device() but not zram_make_request() nor sysfs store functions.

This patch changes init_lock into a rw_semaphore. A write lock is taken by
init, reset and store functions, a read lock is taken by zram_make_request().
Also, avoids to release the lock before calling __zram_reset_device() for
cleaning after a failed init, thus preventing any concurrent task to see an
inconsistent state of zram.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
staging: zram: prevent accessing an unallocated table when init fails early

When the allocation of zram->table fails, we set zram->disksize to zero
to prevent accessing the unallocated table entries during cleanup.
However, we currently don't take this precaution when the initialization
fails earlier.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
zram: Fix sparse warnings

Fixes sparse warning:
zram_drv.c:666:6: warning: symbol 'zram_slot_free_notify' was not
declared. Should it be static?

Also, max_zpage_size is now size_t just to be consistent with data-type
of other variables maintaining sizes of various kinds.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Staging: zram/zram_sysfs.c: Fixed call of obsolete function strict_strtoX

As reported by checkpatch.pl strict_strtoX is obsolet and should be
replaced by kstrtoX.

Signed-off-by: Sergey Datsevich <srgdts@gmail.com>
Signed-off-by: Bjoern Meier <bjoernmeier@hotmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Staging: zram: Add a missing GFP_KERNEL specifier in zram_init_device()

The allocation of zram->compress_buffer is misssing a GFP_* specifier.
This is equivalent to GFP_NOWAIT but it is more likely a omission.
Since the allocation just above it uses GFP_KERNEL, there is no reason
to use GFP_NOWAIT here. Therefore, add GFP_KERNEL.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
zram: simplify and optimize zram_to_dev()

Date	Mon, 3 Jun 2013 23:42:13 +0800

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
zram: avoid invalid memory access in zram_exit()

Date	Mon, 3 Jun 2013 23:42:14 +0800

Memory for zram->disk object may have already been freed after returning
from destroy_device(zram), then it's unsafe for zram_reset_device(zram)
to access zram->disk again.

Fix it by holding an extra reference to zram->disk before calling
destroy_device(zram).

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
zram: destroy all devices on error recovery path in zram_init()

Date	Mon, 3 Jun 2013 23:42:16 +0800

On error recovery path of zram_init(), it leaks the zram device object
causing the failure.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
zram: avoid double free in error recovery path of zram_bvec_write()

Date	Mon, 3 Jun 2013 23:42:17 +0800

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
zram: avoid access beyond the zram device

Date	Mon, 3 Jun 2013 23:42:18 +0800

Function valid_io_request() should verify the entire request doesn't
exceed the zram device, otherwise it will cause invalid memory access.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
zram: protect sysfs handler from invalid memory access

Date	Mon, 3 Jun 2013 23:42:20 +0800

Use zram->init_lock to protect access to zram->meta, otherwise it
may cause invalid memory access if zram->meta has been freed by
__zram_reset_device().

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>